Glowing ore ingot is a crafting component in The Witcher 3: Wild Hunt that is needed to craft dimeritium ingot.
Crafting Requirements 
In the base game it must be crafted, but with the Blood and Wine expansion it can also be found as random loot in Toussaint, or purchased from the following merchants:
- Armorer in Hauteville
- Blacksmith in Belgaard Manor, after he is rescued
- Lazare Lafargue in his workshop
- Trentin in his workshop in Hauteville
It can also be obtained by dismantling most base game craftable Relic swords, superior/mastercrafted level witcher gear swords and chest armors, enriched dimeritium ore, and the following lootable items: